U.S. Pat. No. 4,965,330 discloses that N-phenyl norbornene dicarboximides can be incorporated by metathesis ring-opening polymerization into polymers and copolymers having high glass transition temperatures (Tg). For instance, poly(N-phenyl)cyclopentyldicarboximide vinylene, a homopolymer prepared from N-phenyl norbornene dicarboximide, exhibits a Tg of about 225.degree. C. Poly(N-p-chlorophenyl)cyclopentyldicarboximide vinylene, a homopolymer prepared from N-p-chlorophenyl norbornene dicarboximide, exhibits a Tg of about 230.degree. C. And, poly(N-pcyanophenyl)cyclopentyldicarboximide vinylene-co-(N-phenyl)cyclo-pentyldicarboximide vinylene, a copolymer prepared from N-p-chlorophenyl norbornene dicarboximide and N-phenyl norbornene dicarboximide, exhibits a Tg of about 246.degree. C.
Although N-aryl norbornene dicarboximide monomers can exist in both an endo and exo stereoisomeric form, the endo stereoisomer is not especially reactive in the formation of polymers. For instance, a low yield of a low molecular weight polymer is the typically result of polymerizing an endo stereoisomer of an N-aryl norbornene dicarboximide monomer. Exo stereoisomers of N-aryl norbornene dicarboximide monomers are more adapted to polymerization to high yields of high molecular weight polymers. The less reactive endo stereoisomers of N-aryl norbornene dicarboximide monomers have relatively lower melting temperatures than the exo stereoisomers, allowing for methods of separating the isomers, e.g. by melt crystallization. Because exo stereoisomers of N-aryl norbornene dicarboximide monomers typically have melt temperatures greater than 200.degree. C., polymerization is most typically effected in solutions. For instance, U.S. Pat. No. 4,965,330 reports that the exo stereoisomeric form of N-phenyl norbornene dicarboximide has a melting point of about 200.degree. and the exo stereoisomeric form of N-p-cyanophenyl norbornene dicarboximide has a melting point of about 228.degree.. Melt polymerization is difficult because the high temperatures typically required to melt aryl norbornene dicarboximide monomers can be detrimental to the resulting polymer.